Multiple electrode arc welding



I Feb. 24, 1948. 1. 'HARTER ETAL 2,436,337

MULTIPLE ELECTRODE A'RQWELDI'NG Filed Deo. 22, 1944 6 Sheets-Sheet 2INVENTORS Isaac Harte! BY [Va/7 FMZWHZ ATTORNEY Feb. 24, 1948. l. HARTERETA]... 2,436,387

MULTIPLE ELECTRODE ABC WELDING Filed Dec. 22, 1944 6 Sheets-Sheet 3fsaac Harrier Evan F M15027 a Ernesz C Huge lNVENTORS ATTORNEY Feb. 24,1948. 1. HARTER ET AL 2,436,387

MULTIPLE ELECTRODE ABC WELDING Filed Dec. 22, 1944 6 Sheets-Sheet 4 120202 60? 60 [7X VOLTS v 204 2/ 5 Ix VOLTS VOL i; 9

(Y .92 /78 .9/ /x /7 /X J 78 6 0 M ]/76 lAMP-Sl 90 N v LAMPS W IsaacHarte! 60 PHASE RELATIONS fvanFMfi/son fl Ernest C. ffuge INVENTORJ /-zq. 6

' Feb. 24, 1948. 1|. HARTER ET AL 2,436,387

MULTIPLE ELECTRODE ABC WELDING Filed Dec. 22, 1944 6 Sheets-Sheet 5 1202, 2 6; 120?! 'IZO 7x 6) VOLTS 3 204 206 VOLTS v VOLTS /X AMPS .90

VOL r5 AMPS 2/0 120 PHASE RELAT\ON5 120 PHASE RELATIONS [5420c Harer 516227 M/JOI? my. 9 fiavEfiT sz 'ATTORNEY Feb. 24, 1948. 1. HARTER ET AL2,436,387 MULTIPLE ELECTRODE ABC WELDING 6 Sheets-Sheet 6 Filed Dec. 22,1944 Fig/0 Patented Feb. 24, 1948 UNITED STATES PATENT OFFICE MULTIPLEELECTRODE ARC WELDING Isaac Harter and Evan F. Wilson, Akron, and

Ernest 0. Huge, Barberton, Ohio, The Babcock & Wilc assigncrs to oxCompany, Rockleigh,

10 Claims.

This invention relates to metallic arc welding. More particularly, theinvention is concerned with improvements in arc welding wherein aplurality of metallic electrodes are simultaneously employed withphase-spaced arcs producing a pool of weld metal common to all of thearcs.

A general object of the invention is to so im prove metallic arc weldingprocesses as to effect increased deposits of weld metal per unit of timeand unit of energy employed, and thereby reduce the overall cost ofwelding.

Among other objects of the invention is the attainment of a high thermalefficiency which permits the fusing of an increased amount of electrodemetal per unit of power input.

Other objects of the invention include; a ducticn of time required forslag removal between successive weld metal deposits; 3, reduction in thenumber of passes required for thick plate welding; and the reduction ofweld defects.

The invention will be described with reference to the accompanyingdrawings some of which illustrate apparatus for eiiect'ing the method.

In the drawings:

Fig. l is a front elevation of multiple metallic arc welding apparatusincluding phase-spaced electrodes;

Fig. 2 is a side elevationof the apparatus illustratediin Fig. 1;

Fig. '3 is a vertical section through a weld zone of the multiplephase-spaced metallic arcs;

Fig. 4 is a diagrammatic view indicating a multiple are system in whichthe 60 phase relationship circuits are shown;

Fig. 5 is a diagrammatic view further indicating the arrangement of theelectrodes in the 60 phase-relationship;

Fig. 6 shows a plurality of curves indicating the separate electrodecurrent waves and the reactions between the various electrode currentsinvolved in the system in which the arcs are 60 phase relationship;

Figs. '7, 8, and 9 pertain to the illustrative multiple are system inwhich the respective electrode circuits are in 120 phase relationshipand these figures are, respectively, similar in type and character toFigs. 4, 5, and 6; and

Fig. 10 is a diagrammatic View showing the electrical hook-up for themultiple electrodes.

The apparatus indicated in Figs. 1, 2, and 10 is so constructed that aplurality of arcs can be run simultaneously. It involves a common drivecarriage 8 which is traversed over a longitudinally extending fixedguide or support it] by the combination gear head speed ranger I2. Threeautomatic welding heads i4, i5, and i8 are ntounted to the carriage soas to maintain their metallic electrodes I, 2 and 3 in downwardlyconverging relationship toward a common position along the weld zone.The electrode of each head is advanced by an independent drive mechanismincluding a motor such as that indicated at 26 in Pg. 2. Furthermore,each welding head drive mechanism has its own independent arc control bywhich the voltage of the arc and the rate of feed of the electrode arecoordinated. For example, the feed of the electrode 3 is regulatedthrough connectors '38 and leading from its w ding head to the arccontrol device This device has leads 36 and 33 connec l, respectively,to the electrode 3 and the work so that the voltage of the are between51E electrode 3 and the work 433 may be maintained within predeterminedlimits by appropriate increase or decrease in the rate of feed of theelectrode through the welding head Hi. The are control device it isconnected by leads and i l to a source of power. The arcs between theremaining elec trodes 2 and I and the work as are -.dependentlyregulated by similar control dev c the electrodes being supplied fromthe reels which are rotatably supported by the traversi. g ca iage at anelevated position, as indicated in the d. .wings. Each automatic arccontrol 1. nched with 220 volt alternatin current which half-waverectified to drive the 229 volt D. C. e rode feed motor 26. The controlsare so adapted the arc voltage may be set any point from 25 t 40 volts.

From Fig. 10, it will be noted that the welding circuit may be connectedin either or 120 phase relationsh ps. In the 120 system, the phaserelationships are symmetrical and for the 60 system the center or Y lead(see 10) is reversed (or, in other words, leads X" and Y" on thetransformer 6i are reversed) giving a 60 relationship.

Power for the multiple arc apparatus is furnished by two 160 k. v. a.distribution transformers 55 and 55 connected in open delta to transformthe 2300 volt, 3-phase power of the line elements X Y, Z, of 10 to theS-phase 220 volt current of the lines X, Y, and Z.

Between the electrodes 5, 2, and. 3 and the line elements X, Y, and Zare three 750 ampere welders 6i 6!, 62 each involving a transformer witha 220-vclt primary and an or volt secondary with a variable reactance inseries.

Between the respective welding transformers 60,

3 6|, 62 and the electrodes I, 2, and 3 are the contactor control boxes66, 61, and 68.

One terminal of the secondary of each of the transformers 60, BI, 82 isconnected with the work 40 by conductors such as those indicated at I0,II, I2 in Fig. 10, and the other terminal of each secondary is connectedthrough one of the contactor control boxes with one of the electrodes.The latter connections may be eifected by such conductors as thoseindicated at I5, I8, 11, I8, I9, and 80. Separate volt-meters 85, 86,and 81 are connected between the conductor I3 and the separate linesleading to the separate electrodes I, 2, and 3. Such volt-meters arealso indicated as similarly connected in the hookups indicated in Figs.4 and 7 of the drawings.

The current supplied to the separate electrodes and their arcs is, inoperation, continuously indicated by ammeters 90-92 connected into theseparate electrode circuits, as also indicated in Figs. 4 and '7. Suchinstruments may be, for convenience, secured to a panel fixed to drivecarriage 8.

As indicated in Figs. 1 and 2, the drive carriage 8 includes ahorizontal platform I upon which there are supports I02 and I04 for theseparate electrode reels 50, and 52. This platform also carries thespeed ranger I2 which includes an electric motor and variable speedtransmission operating a pinion I I0 meshing with the teeth of a rack II2 fixed to the support I0.

The drive carriage 8 and its pertinent devices overhang the fixedsupport or guide I0 to considerable extent, and for this reason thecarriage has a downward extension I20 which rotatably supports a guideroller I22 contacting the lower edges of the support I0 as indicated inFig. 2.

- The platform I00 has fixed thereto a vertical rambracket I24 havingvertical bores for receiving the upright vertical rods or rams I26.Preferably there are two of the brackets I24 and two rams I26 fixedlyconnected at their lower ends by a horizontal ram bracket I28, thisconstruction supporting the welding heads and their control mechanismsfor vertical and horizontal adjustments with reference to the platformI00. Vertical adjustment of the welding heads may be effected by meansof the hand wheel I30 which rotates the shaft I32 to cause the ram I26to move vertically in the brackets I24. The upper part of the shaft I32is screw-threaded as indicated in Fig. 1, and is threaded through anintermediate part of the bracket I24. Below this part of the shaft theremay be a collar fixed against movement longitudinally of the shaft andagainst movement vertically with respect to the horizontal ram bracketI28.

In the lower part of the horizontal ram bracket I28 there may be twohorizontal bores for slidably. receiving horizontal rams such as thatshown at I34. The outer ends of the rams I34 are rigidly joined by ahead slide I36 to which the inner welding head brackets I38-I40 areadjustably secured.

Outer welding head brackets such as that indi- "cated at I42 are securedto the inner brackets -I38I40 so as to be adjustable about thehorizontal axes of the worm gears I44 each of which is fixed to an outerbracket I42, The outer end of each bracket I42 is forked so as toprovide journal supports for one of the trunnions I46.

This arrangement provides supports for the welding heads I4, I6, and I8and enables each of the welding heads to be swung about the axis of atrunnion I45 by an adjuster I48. For rotatably adjusting each of thewelding heads and its bracket I42 about the axis of the worm wheel I44,there is an adjusting wheel I54 for each welding head, and after anysuch adjustment is made, the pertinent welding head is locked in itsadjusted position by swinging one of the clamping levers I56I58 to itslocking position,

Each of the welding heads I4, I8, and I8 carries a leveling passconstruction I80 having journaled therein guide rollers I62 and I64 forthe associated electrode.

For causing the electrodes I, 2, and 3, their arcs, and the weldingheads to move through an inclinedpath parallel to the work and thebottom of the welding groove as they are indcated in Fig. 3, the drivecarriage is provided with a combination motor and-speed ranger I10 forrotating the shaft I32 through the gears I12 and I14. The speed at whichthe shaft I32 is operated is coordinated with the advance of the entiredrive carriage along the fixed guide or support I0, to produce therequired inclined path of movement.

To enhance the inherent characteristics of the illustrative multiple arcmethod to da p the molten weld metal to a high degree and to prevent thepool from running ahead of the arc, the

.method may be practiced with the work inclined to the horizontal AB, asindicated in Fig, 3. The electrode 2 and 3 are also inclined to enhancethese same desirable results. For instance, the electrode I is shownvertically arranged and the electrode 2 inclined rearwardly anddownwardly toward the pool I with its axis at 10 to the axis of theelectrode I. The leading electrode 3 is further inclined so its axis isat an angle of 20 to the axis of the electrode I.

In the method illustrated in Fig. 3 relative movement of the electrodesand the work 40 is such that the electrode may be considered as weldinguphill. When the work is fixed, the electrodes move in the direction ofthe arrow I82.

The illustrative method is also adapted for advantageous use with fluxcoated electrodes, and it is also used with improved results in the fluxsmothered type of welding. Its use in the latter is indicated in Fig. 3of the drawings. Here, the base of the weld groove is indicated at I90,a layer of unfused welding flux at I92, and the solidified weld metal atI94. Above the latter is a stratum I96 of solidified or frozen fiuxwhich has previously been fused by the action of the arc. Above thestratum I is a layer I98 of granular flux which has not been changed bythe process.

As compared to the results of welding with a single electrode, thepractice ofv the illustrative method, with the use of three electrodes,effects more than three times the deposit of weld metal per unit oftime. Thus, there is a considerable reduction of welding time forproducing a given weld. Furthermore, the illustrative method increasesthe heat input per unit of length of weld seam, and thus decreases therate of cooling and decreases the hardness difference in the metal ofthe weld zone or adjacent thereto. The danger of undesirable residualstress patterns in the metal is also reduced.

The illustrative method also effects single pass welding whicheliminates trouble from undercutting or side-washing. By reason of thegreater stability of the polyphase arc, the illustrative method iseffected with a lower open circuit voltage and therefore with acorrespondingly lower transformer rating in k. v. a.

The illustrative method also provides for su- .perior slag holdingproperties by utilizing dinerare at volts, the middle arc at volts,,and

the following arc at volts, the slag holding properties of the methodare considerably improved. The thermal efficiency of the method is high,and the method accomplishes a further reduction in overall welding timeby reducing the time required for slag chipping and removal, andreducing set-up time.

The illustrative method involves the merging of the arcs into a commonpool of weld metal, and coincidence of maximum magnetic effects in thearcs are avoided by placing the welding currents out of phase with eachother. Under these conditions, the arc blow is reduced even whencompared with the ordinary single phase A. C. arc, which is definitelysuperior to the D. C. arc.

The combined arc of the illustrative method is elongated so that theheat is distributed principally in the direction of travel or length ofthe welds. This permits a larger are without increasing the width of theweld groove, a result which would notbe possible if the increased ratesof weld metal deposition were sought to be effected by the use of anequivalent single current in a single electrode or larger diameter. Thusless weld metal per inch length of groove is required.

With the electrode inclinations of the illustrative method, the slag ispushed backward, and supplies good coverage to protect the molten pool.

When welding in a groove with three electrodes in line it is necessaryto provide sufficient width so that the slag may flow between theelectrode and wall rather than through the arcs. The effect of theinclination is to afford a head differential between the leading andtrailing edge of the are so that the slag will fiow toward and remain atthe trailing end of the arc.

Fig. .4 isa diagrammatic view indicating the electrical characteristicsof the welding system when the electrodes l, 2, and 3 are in 60 phaserelationship. The ground current may be indicatedby an ammeter 2 3%connected into the ground cable #3 and the voltage across the lines itand 8 3 may be indicated by an instrument 2t2. The voltmeter 25%indicates the voltage across the lines'iii-lii, and the voltmeter 29%indicates the voltageacross the lines To and 80.

In the operation of the system with the electrodes in 60 phase relation,as indicated in Figs.

4 and 5, the arcs between the work do and the electrodes 2, and 3 arepredominately attractive. This is indicated by the diagram of Fig. 6 andit has been proven by the visual evidence offered by the film of thearcs produced by a pin hole type of stroboscopic camera. The record thusproduced in actual practice corresponds quite closely with theindications of the reaction curves lA,-ZA, and 3A of the Fig. 6 diagram.In this diagram, the curves or waves i, 2', and 3' are for the respectivelectrodes with corresponding members. The curve IA shows the reactionbetween the currents of electrodes 5 and 2 which are 60 apart. It willbe noted that the major part of this curve indicates attractive charac-*teristics of the arcs of electrodes l and 2.

The curve 2A represents the reaction between the currents 2' and 3'which are 60 apart. The major part of this curve also indicates theattractiveness of the arcs of electrodes 2 and 3. Curve 3A representsthe reaction between the currents of electrodes {and 3 which are 120apart and themajor part of this curve, similar in degree tothe aboveindicated parts of the other curves [A and 2A, indicatesthe predominant.repulsiveness of the arcs of electrodes 1 and 3. Thuathe predominatingcharacteristic of the three arcs in combination isthat the arcs areattractive.

The illustrative system and method, with the arcs in 63 phaserelationship thus has the advantage that the arc act more likea singleare. When coated electrodes are employed the slag is more efiectivelydammed and prevented from running ahead of the electrodes. This probablyaccounts, at least in part, for the superior results of the illustrativemethod with the 60 arrangement, particularly as regards porosity andslag inclusion. With the arcs in the 60 phase relatic .ship, theconcentrated pool of molten metal results in improved thermalconditions, involving slower cooling rates allowing more time for gas toescape. There is also improvement in the refinement of the weld metal byreason of its slower rate of solidification.

-Wiien the electrodes are arranged in the 123 phase relationship asindicated in Figs, 7 and 8 the arcs between the electrodes 1, 2, and 3and the work iii are predominately repulsive. However, with thisarrangement the return ground current, indicated by the ammeter 2H! (seeFig. 2''), is Zero which eliminates loss in the ground lead 73. I

In the Fig. '7 hookup, the voltages indicated by the instruments 2&2,2G8, and 236 will usually be of the same order.

In the Fig. 9 diagram, illustrating the currents for the electrodes inthe 120 phase relationship, the curve l, 5, and 6 illustrate thecurrents for the respective electrodes. They are 120 apart. Th curve 4Arepresents the reaction between. current 4 and 5, and the curve 5A isthe reaction between the currents 5 and 5. The curve 3A is the reactionbetween currents 4 and 6.

Since the electro-motive forces between the arc streams arepredominantly repulsive, the overall J are Zone tends to be longer (withthe electrodes in the line of welding and phase-spaced 128) and narrowerthan when the arcs are in (30 phase-spaced relationship.

With the system involving the electrodes in 126 phase relationship themaximum welding current obtainable from each welding trans former hasbeen found to be amperes higher than for the 50 hook-up due to the zeroground current of this arrangement, and the elimination of impedancedrop in the ground lead 13.

When the illustrative method and system are utilized in the cladding ofsteel with an alloy, the latter is deposited over a wide path by themultiple electrodes preferably arranged in a row transverse to thedirection of relative-movement between the work (the steelbody) and theelsctrodes. When a plurality of groups of the latter are employed alarge area of steel is clad during each pass, the alloy from theelectrodes being deposited under a layer of flux.

We claim:

1. In a method of arc Welding maintaining a plurality of metal fusingand metal depositing electric arcs along a weld zone, energizing thearcs from a single polyphase source, maintaining a uniform phasedifference of less than 186 be tween the arcs, independently andcontinuously supplying weld metal to each are as metal is fused thereby,co-ordinating relative movement be tween said arcs-and the Weld zonewith the rate of fusion, and independently controlling the voltpluralityof metal fusing electric arcs mergin into a common metallic pool in aweld zone, en-

ergizing the arcs from a single polyphase source of electrical energy,maintaining a uniform phase spacing of 60 between the arcs and therebycausing said arcs to be predominantly attractive, co-ordinating relativemovement of the merging arcs and said pool along the weld zone with therate of deposition of fused weld metal, and independently controllingthe voltage of each are.

3. In an arc welding system, a plurality of consumable metallicelectrodes arranged in the line of welding, independently operatingwelding heads simultaneously feeding the electrodes toward their closelyadjacent arcing ends disposed over the zone of a weld seam, meanseffecting relative movement of the welding heads and the weld zone toprogressively produce a weld seam, the electrodes converging downwardlytoward a common pool of fused weld metal with the leading electrodeinclined downwardly and rearwardly toward the arcing end of a trailingelectrode, a multiple phase electric system by which the electrodes andtheir merging arcs are in 60 phase-spaced relationship, and independentand automatic arc-voltage control for each electrode and its feedingmeans.

4. In an arc welding system, a plurality of downwardly convergent fluxcoated electrodes normally having arcs merging in a common weld metalp001, independently operating welding heads simultaneously feeding theelectrodes toward their closely adjacent arcing ends disposed along aweld seam zone, a multiple phase electric system by which the electrodesand their merging arcs are maintained in phase-spaced relationship,independent arc-voltage control for each electrode and its welding headfeeding means, traversing means causing progression of the arc weldingalong a weld seam, and means maintaining the leading electrode inclineddownwardly and rearwardly toward the common areing zone at an acuteangle to the trailing electrode.

5. In a multiple metallic arc welding system, granular weld flux atleast partially filling a groove in which the weld is to be made, threeindependently controlled metallic electrodes converging downwardly andarranged in succession along a single weld line along said roove,traversing means for effecting relative motion between the depositedweld metal and the electrodes, means maintaining the trailing electrodesubstantially normal to the line of the weld and maintaining theremaining electrodes inclined downwardly and rearwardly toward thearcing end of the trailing electrode and at successively smaller anglesthereto, means including a three phase electric system causing saidelectrodes to form 60 phase-spaced arcs merging in the same metallicpool in said groove and beneath said flux, independentl operable weldingheads for advancing the electrodes toward said pool, and independentarc-voltage controls for the sepa rate arcs and the separate weldingheads.

6. In a method of arc welding, simultaneously maintaining a plurality ofphase-spaced metal fusing and depositing electric arcs along a weldzone, causing relative movement between said arcs and the work,independently and continuously supplying weld metal to each arc, andmaintaining the voltages of the arcs at increasing values from theleading are to the trailing are by independently controlling the voltageof each are.

7. In a method of arc welding, maintaining a plurality of metal fusingand phase-spaced electric arcs merging into a common metallic pool in aweld zone, energizing the arcs from a single polyphase source ofelectrical energy, maintaining a uniform phase spacing of between thearcs and thereby causing said arcs to be predominantly attractive,independently controlling the voltage and length of each arc to maintainthem at predetermined values increasing from the leading arc to thetrailing arc, and causing relative movement of the merging arcs and thework to effect progression of the welding action along a welding zone.

8. In a multiple arc welding system, granular weld flux at leastpartially filling a groove for the weld, three independently controlledmetallic electrodes in line lengthwise of the groove, means including athree phase electric system causing said electrodes to form phase-spacedarcs merging in the same metallic pool in said groove and beneath saidflux, said means including Y separate phase connections for the separateelectrodes and other electrical connections to a terminal for each areand independently operable welding heads feeding the electrodesconvergently toward said pool, means causing relative movement betweenthe deposited weld metal and the electrodes longitudinally of the grooveto efiect progression of the welding along the groove, the leadingelectrode being inclined downwardly and rearwardly toward the pool Whilethe trailing electrode is closer to a position normal to the line ofwelding, and independent arc-voltage controls for the separate weldingheads.

9. In an arc welding system, a plurality of consumable flux coatedmetallic electrodes, independently operable welding heads simultaneouslyand independently feeding the electrodes toward their closely adjacentarcing ends disposed over the zone of a weld seam, a three phaseelectric system including a. Y polyphase connection by which theelectrodes and their merging arc are in a 60 phase-spaced relationship,and independent arc-voltage control means for each electrode and itsfeeding means.

10. In a method of cladding steel by are welding, simultaneouslymaintaining a plurality of phase-spaced metal fusing and depositingelectric arcs closely spaced in a zone transverse to the claddingprogress, causing relative movement between said arcs and the steel,independently and continuously supplying weld metal to each are as thecladding progresses, and inde pendently controlling the voltage of eachare by varying the rate of supply of weld metal thereto.

ISAAC HARTER.

EVAN F. WILSON.

ERNEST C. HUGE.

' REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,340,056 Kenyon May 11, 19201,493,903 Bennett June 24, 1924 2,191,469 Hopkins Feb. 2'7, 19401,371,094 Holslag Mar. 8, 1921 2,191,482 Hopkins Feb. 27, 1940Certificate of Correction Patent No. 2,436,387. February 24, 1948.

ISAAC HARTER ET AL.

It is hereby certified that errors appear in the printed specificationoi the above numbered patent requiring correction as follows:

Column 2, line 1, for the numeral 15 read 16 line 2, same column, forthe words mounted to read mounted on; column 5-, line 64, for membersread numbers; column 8, line 17, claim 7, for welding read weld; line47, same column, claim 9, for are read arcs;

and that the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Ofiice.

Signed and sealed this 5th day of July, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

Correction Patent No. 2,436,387. 4 ISAAC HARTER ET AL.

eariin the printed specification of the above ertified that errors appollows:

It is hereby c quiring correction as f numbered patent re r the numeralColumn 2, line 1, f0 ed to read m0 column 8, line 17, claim d with thesecorrections for arc reed arcs;

and that the said Letters Patent should be rea the same may conform tothe record of the case in the Patent Office.

Signed and sealed this 5th day of July, A. D. 1949.

15 read 16 line 2, same column, for the words muted on; column 5, line 6for members reed numbers; ld; line 47, same column, claim 9,

7, for welding reed we therein that THOMAS F. MURPHY,

Assistant G'ommissioner of Patents.

